Screen plate for paper making machines



Sept. 24, 1935. F, DUSTAN ,1

SCREEN PLATE FOR PAPER MAKING MACHINES Original Filed May 3, 1954 Wan/f War/4x2 Patented Sept. 24, 1935 FATENT OFFICE SCREEN PLATE FOR PAPER MAKING MACHINES Frank Dustan, Fitchburg, Mass,

assignor to William A. Hardy & Sons (30., Fitchburg, Mass., a corporation of Massachusetts Original application May 3, 1934, Serial No. 723,759. Divided and this application October 3, 1934, Serial No. 746,687

3 Claims.

This is a division of my application for patent, Serial No. 723,759, filed May 3, 1934.

The principal objects of this invention are to provide a screen plate adapted to be used in the ordinary way, the screening surfaces of which can be made of thin sheets of stainless steel or other non-corrosive metal and to make the plate in sections obtaining the rigidity from supporting cross straps, thus providing a very rigid plate with less material and less cost.

A further object is to provide a screen plate Without surfaces directly adjacent to the under side of the narrow screening slits, such as those formed in the ordinary thicker type of bronze screen plate, and between which the screened pulp often collects and clogs, necessitating the removal and cleaning of the plate.

Other objects and advantages of the invention will appear hereinafter.

Reference is to be had to the accompanying drawing, in which Fig. l is a plan of a screen plate constructed in accordance with this invention;

Fig. 2 is an end view as indicated by the arrow 2 in Fig. 1, and

Fig. 3 is a sectional view on the line 3-3 of Fig. 1.

In using a screen plate the pulp flows over the screen and is drawn through the slots by means of a diaphragm, not shown. The bronze screens heretofore commonly used have been of considerable thickness, about three-eighths of an inch, in order to give them the requisite strength. A series of channels or grooves are milled on the under side of the plates, the depth of these grooves extending very nearly to the upper surface of the plate. These grooves are of considerable width at the under surface, tapering or decreasing in width as they extend up into the plate. Fine slits are cut through from the bottom of these grooves to the top surface of the plate, through which the pulp is screened. The function of the metal of the lower portion of the plate between the milled channels is merely to strengthen or sustain the upper slitted screening surface.

The said milled channels are made tapering and broadest at the lower surface of the plate in order that the pulp, after having passed through the narrow slits, may fall away freely, but in practice it is found that the pulp often collects and clogs in these channels necessitating the removal and cleaning of the plates involving a considerable loss of time and. also additional wear and tear on the plates due to the cleaning opera- 5 tion.

My plate is made of a series of sections of stainless sheet steel or other rustless material. The screen plate is shown as composed of a series of stainless steel, or other non-corrosive metallic, wide short channel sections 30. These channel sections are assembled and spot-welded to cross strips 3|, which act as butt straps and also form cross trussesin the assembled screen. The side sills 32 are spot-welded to flanges 34 which are bent down at opposite edges of the channel sections. These are assembled first. The end sills 33 are fitted to the under sides of the end sections and spot-welded to them. These sills receive screws or other means used to fasten the screen plates to the vats. Before the sheets composing the screen are formed into the wide, short channel sections they are slitted, as indicated at 35.

This construction has only the short cross members 3| and 33 which have to be brought into intimate contact with the under side of the wide short sections and these short, separate members 3| and 33 can easily be individually fitted in close contact with the top sheet. These joints are spot-welded all over. 30

The construction of a screen made up of sections of stainless sheet steel or other material, previously slitted, and having flanges 34 is a distinct advance in this art. These flanges eliminate an'under side joint that otherwise would occur at this point. Also they form a vertical surface to which the side sills are welded. A lighter and at the same time more rigid plate is provided and the under side faults present in former constructions have been eliminated.

Having thus described my invention and the advantages thereof, I do not wish to be limited to the details herein disclosed, otherwise than as set forth in the claims, but what I claim is:

1. As an article of manufacture, a screen plate comprising a series of slitted channel plates of thin strong'non-corrosive metallic material, each sheet extending across the plate, their adjacent flat edges being butted together and. their side edges extending downwardly, cross strips under the joints between adjacent plates and welded to them, and side sills welded to the down turned side edges.

2. As an article of manufacture, a screen plate made up of a series of sheets of thin non-corrosive metal, each sheet extending across the screen plate and channeled by the turning down of its end edges, the side edges being fiat, each sheet being slitted in the direction of its length, the fiat edges of the adjacent sheets abutting against each other, cross strips under the joints between adjacent sheets and permanently secured thereto,

and side sills secured to the down turned edges of the sheets.

3. The method of forming a screen plate which consists in slitting a sheet of thin non-corrosive metal, turning down its end edges at right angles to the plane of the sheet, assembling a plurality of said. sheets edge to edge, welding cross strips to the lower surfaces of the sheets where they abut, and welding side sills to the down turned edges of the assembled sheets.

FRANK DUSTAN. 

